Concentricity error — In an optical fiber, the concentricity error is the distance between the center of the two concentric circles that specify the cladding diameter and the center of the two concentric circles that specify the core diameter. The concentricity error… … Wikipedia

Chuck (engineering) — Self centering three jaw chuck and key with one jaw removed and inverted showing the teeth that engage in the scroll plate. The scroll plate is rotated within the chuck body by the key, the scroll engages the teeth on the underside of the jaws… … Wikipedia